Apparatus for burning residual liquor



Nov. 18, 1958 R. K. ALLEN 2,850,611

APPARATUS FOR BURNING RESIDUAL LIQUOR Filed Jan. 27, 1955 FiG.2

IN V EN TOR.

ROBERT K. ALLEN ATTORNEY United States ParenrC) APPARATUS FOR BURNING RESIDUAL LIQUOR Robert K. Allen, Ridgewood, N. J., assignor to The Babcock & Wilcox Company, New York, N. Y., a corporation of New Jersey Application January 27, 1955, Serial No. 484,417 2 Claims. (Cl. 122-240) The present invention relates to the incineration of pulp residual liquor for the useful recovery of the heat values therein and more particularly relates to the incineration of the residual liquor from the sulphite base cooking liquor and the generation of steam by the combustion of the liquor alone or in combination with another fuel.

The residual liquor obtained from the digestion of cellulosic fibrous materials by a calcium or sodium sulphite base cooking liquor has heretofore been discarded as a waste material due to the lack of a mechanical process for the recovery of the chemicals in the liquor.

Heretofore, the residual liquor has been discharged into streams or bodies of water but such means of disposal create a public nuisance by contamination of the water. Attempts to dispose of the residual liquor by concentration and incineration of the concentrated liquor has not always been economical due to difficulties in burning the liquor and releasing enough heat for useful purposes. However, it is known that the residual liquor can be successfully burned and the heat values therein used in the generation and superheating of a vapor, provided the liquor is burned in conjunction with a high heat content fuel. While the combustion of the liquor alone will hardly release enough heat to generate sufficient steam to concentrate the liquor before incineration, the ash residue is considerably easier to dispose of than when the liquor is in its liquid form. When the liquor is burned in conjunction with another fuel the capital in vestment for vapor generating equipment can be justified provided the two fuels can be burned either separately or in combination in the same furnace.

In accordance with the present invention sulphite residual liquor is burned in suspension in the upper portion of an elongated furnace, with the combustion products of the residual liquor passed through a zone of combustion where a high heat value fuel is burned in suspension. Thereafter the mingled products of both fuels is subjected to a change of flow direction with a major portion of the non-combustibles of both fuels separated from the gaseous combustion products. The separated non-combustibles are discharged from the lower end of the furnace while the hot gaseous products of both fuels pass from the furnace over heat exchange elements for the recovery of heat therefrom. The residual ash from both fuels, which is discharged from the furnace, can be economically disposed of while in the solid state.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described a preferred embodiment of the invention.

Of the drawings:

Fig. l is an elevation, partly in section, of a steam with a substantially upright generating and 'superheating unit constructed and at-- ranged for the combustion of sulphite residual liquor in accordance with the present invention; and

Fig. 2 is a partial section of the unit taken on the line 2-2 of Fig. 1.

In the embodiment of the invention shown in the drawings the residual liquor resulting from the digestion of wood is burned in a vertically elongated furnace with pulverized coal. The non-combustible ash residues of both fuels are mingled for common removal from the furnace and the hot gaseous products of combustion from both fuels are passed over the tubular heat exchange elegeneration and superheating.

ments of the boiler for the of steam.

As shown, the vapor generating unit includes upperbanks of convection tubes 12. The furnace 13 for the combustion of concentrated residual liquor and pulverized coal is defined by walls containing vapor generating tubes: connected into the circulatory system of the steam gen-- The front wall 14 of the furnace 13 is faced by a row 15 of elongated vapor generating tubes extending; from an upper header 16 in the top of the furnace to a. lower header 17 adjacent an ash hopper 18 of the furnace. The upper portion of the tube row 15 is horizontally inclined, forming a part of a furnace roof 20 while the:

erator.

lower portion 21 of the front wall tube row 15 is extended. in a downwardly and rearwardly inclined direction to form a side of the hopper 18. The upper header 16' extends transversely across the top of the furnace intermediate the distance between the upper steam and water drum 10 and the furnace front wall 14.

- The rear wall 22 of the furnace 13 is faced by a row 23 of vapor generating tubes, the lower portion 24 of which forms the rearward side of the hopper 18 and opens to a lower transverse header 25. The upper portion of the row 23 is bent to form nose baflle 26 which projects inwardly of the furnace 13, and extends upwardly and rearwardly to define the lower edge of a superheater cavity, and the row of tubes is thereafter laterally displaced to extend across the flue gas outlet 37 from the;

with upper and lower headers 30 and 31 respectively,

which are connected into the circulatory system of the boiler.

As shown in the drawings, the furnace 13 is provided division wall 33 formed of vapor generating tubes depending from the header 16 and extending downwardly from the roof 20 to a position spaced above the tube portion 24 of the hopper 18. The division wall is closer to the rear wall 22 than to the front wall 14, and the upper portion of the tubes aretangent to provide a substantially gas tight wall bounding the rearward side of a combustion space 35 in the upper portion of the furnace 13. The lower portion of the tubes in the division Wall 33 are extended in a long radius bend to project in a generally horizontal direction, opening to uprightheaders 34 disposed on opposite sides of the furnace side walls (see Fig. 2).

A pendent superheater 36 is positioned behind the wall 33 adjacent the flue gas outlet 37 from the furnace 13, and above the nose baffle 26. Thus, in the construction described, heating gases produced in the combustion space 35 pass downwardly around the lower end 38 of the division wall 33 and upwardly over the superheater surfaces toward the furnace outlet 37. Thereafter the partially cooled heating gases pass over the convection heating banks 12 of the boiler and are discharged through an Patented Nov. 18, 1958 3 outlet 40 to an economizer, air heater or the like (no shown), and thence to the atmosphere. A dust collect: ing hopper 41 is provided beneath the convection tube banks 12 and the drum 11, with the hopper having an upright transversely. extending plate 42 therein. The

lower end of the plate 42 will normally be submerged,

in the dust collected in the, hopperto form a seal and to thereby avoid bycpassing of heating gases around the convection tube banks 12.

T heupper portion of the walls of, the combustion space 35 is lined with refractory, material 43 to form a heat reflective surface. The refractory material 43, may be an initially plastic chrome ore installed on studs welded to the tubes of the wall tube rows 15, 27 and the division wall 33, and facing the combustionspace 35.. The retrace tory material 43 lining the combustion space 35 covers the tubes to provide a hot zone for the combustion of the residual liquor, as hereinafter described. Adjacent the top of the furnacev plurality of spaced ports 44 are formed in the side walls 27 to accommodate atomizing nozzles 45 for the, introduction ofresidual liquor into the combustion space. Combustion air for the residual liquor is introduced through the ports 44 from an external housing 46 which encloses all of the ports on each side of the furnace. In the embodiment of the invention shown in the drawings a group of six ports 44 and nozzles 45 are installed in each of the opposite side walls. 28 so that the stream of fuel and air, from one port impacts a corresponding stream from a port in, the opposite side wall.

The front wall 14 of the furnace 13 is provided with one or. more ports47 positioned below the lower edge of the refractory lining 43 and at a level above the lower end 38 of thedivision wall 33. In the embodiment shown, pulverized coal and, air are delivered to the fur nace through the port 47 by a pulverized coal burner 48. Pulverized coal is prepared as required in a unit pulverizer 50 and is delivered to the burner 48 through a connecting pipe 51. Air at a superatmospheric pressure, is supplied to the pulverizer 50. by a blower 52 so that the pulverized coal is introduced through the burner 4% in air suspension. For coal drying purposes, preheated air is supplied to the blower through a conduit 53 from the preheated secondary air housing 54 enclosing the burner 48. The amount and temperature of the airdelivered to the blower is regulated by the damper'SS, and a valve 56 in a tempering air. inlet 57, respectively.

Preheated combustion air is obtained from a heater of known type (not shown) which obtains heat from the flue gases passingthrough the outlet 40, and is forced through an insulated conduit 58 by a forced draft fan (not shown). The conduit 58 is disposed an opposite exterior sides of the vapor generator setting and opens to the airihousing 54, with a branch conduit 60 leading from. the conduit 58 to the housing 46;. The amount of combustion air supplied to the furnace is regulated for best combustion conditions forboth fuels.

With the burning mass of residual liquor. moving down:

lating in the hopper 18. The combined solids-are passedthrough an opening 59 at the bottom of the hopper 18, and through an uprightrefractory lined duct 61 to a sluice-way 62, or the like, for periodic or continuous removal of the solids.

While the upper portion of the combustion space 35 is lined with refractory materials to provide desirable high temperature combustion conditions for the low heat content residual liquor, which may contain 30 to 50 percent water, the lower portion of the combustion space 35 and the remainder of the furnace 13 is bounded by vapor gen erating tubes for a high rate of heat exchange with the hot gases of combustion.

While in accordance with the provisions of the statutes I have illustrated and described herein a preferred embodiment of the invention, those skilled in the art will understand that changes may be made in the method of operation and form of the apparatus disclosed without departing from the spirit of the invention covered by my claims, and that certain features of the invention may sometimes be used to advantage without a corresponding. use of other features.

What is claimed is;

I; Apparatus for the incineration of the pulp residual liquor resulting from a sulphite cooking process com-.-

prising walls definingan upwardly elongated. furnace. having a gas outlet in the upper rear portion. and a hopper bottom in the lower portion thereof, means forming a division wall extending downwardly from the roof of said furnace to a position. spaced above said hopper bottom, burner means positioned in the upper portion of said furnace for the introduction of residual liquor and. combustion air thereto, burner means positioned in a wall' of said furnace upwardly adjacent said hopper bottom and at a level spaced immediately above the lower end of said division wall for the introduction of an ash containingsolid fuel and combustion air thereto, and means for passing the mingled products of combustion around the lower end of said division Wall to separate noncombustible solids from the mingled gases of combustion from both fuels before said mingled gases pass to said gas outlet.

2. Apparatus for the incineration of pulp residual liquor resulting from a sulphite cooking process comprising rows of vapor generating tubes and refractory material defining the walls and roof of an upwardly elongated furnace having a gas outlet in the upper portion of a rear wall and a hopper bottom in the lower portion of said furnace, a row of depending tangent tubes forming a division wall extending from side wall to side wall and downwardly from the roof of said furnace to a position spaced above said hopper bottom, burner means positioned intthe upper portion of said furnace for the introduction of said residual liquor and combustion air thereto, burner means positioned in a wall of said furnace upwardly adjacent said hopper bottom and at a level spaced immediately abovethe lower end of said division wall for the introduction of an ash containing solid fuel and combustion air thereto, and means for passing the mingled products of combustion around the lower end of the tubes forming said division wall to separate noncombustible solids from the mingled gases of combustionv from both fuels before said mingled gases pass to said gas outlet.

References Cited in the file of this patent UNITED STATES PATENTS 2,206,265 Saathoif July 2, 1940 2,238,007 Badenhausen Apr. 8, 1941 2,540,060 Simpson Feb. 20, 1951- 

